Sintering method



July 3, 1934. E. w. SHALLOCK S INTERING METHOD Original File a ch 21.195 2 Sheets-Sheet l y 3, 1934. 1-:.w. SHALLOCK 1,965, 20

SINTERING METHOD Original Filed March 21, 1950 2 Sheets-Sheet 2 PatentedJuly 3, 1934 UNITED STATES snv'rsamc METHOD Edward W. Shallock, Chicago,111., assignor to American Ore Reclamation Company, Chicago, 111., acorporation of New York Original application March 21, 1930, Serial No.

Divided and this application October 3, 1932, Serial No. 635,885

1 Claim. (Cl. 266-21) This invention relates to the sintering of ores,flue dust, and other materials containing combustible ingredients, andhas to do more particularly with a method for sintering such materials.

5 res and other materials to be sintered are not uniform and frequentlycontain large proportions of relatively large particles, which may beconsidered as aggregates, as well as considerable proportions ofrelatively small particles, which may 19 be considered as fines. Insintering materials which are composed either entirely or to aconsiderable extent of fines, when the sintering operation is conductedin machines known as the m Dwight and Lloyd type, in which the materialto forated grate, the fine material has a tendency to stop up or clog,more or less, the perforations of the grate with the result that it isfrequently quite diincult to obtain the proper down-draft through themass to assure proper sintering thereof during travel of the grate tothe delivery or discharge end or the machine. Under such conditions,either the material is not properly sintered, or the output of themachine is greatly curtailed due to the necessity of slowing down thespeed of operation. The great majority, and in fact practically all, ofthe materials treated in slntering machines contain an appreciableamount of relatively large particles or aggregates. It is the presentpractice, when sintering such materials in continuously operatingmachines, such as machines of the Dwight and Lloyd type, to deposit thematerial upon the moving grate with the coarse particles or aggregatesand the relatively small particles or fines intermixed indiscriminately,with the result that a certain amount of stoppage of the perforations ofthe grate occurs with resultant slowing down in the sintering operation.40 I have found that this objection can be avoided, and the output of agiven machine greatly increased, by separating the fines and aggregatesof the material to be sintered and forming upon the grate a lower layerof aggregates, and then.

depositing upon this lower layer an upper layer of fines. The lowerlayer of aggregates is loose and porous and will not clog the openingsof the grates so that air will readily pass downwardly through bothlayers of material, after the upper layer of flnes'has been ignited, andcombustion throughout the mass is rapidly propagated with the resultthat the sintering operation can be quickly and satisfactorilyaccomplished in much less time than is now possible under presentpractlce. One of the main objects of my invention is be sintered isdeposited in a layer upon a perto provide a method whereby the materialto be sintered -is separated into aggregates and fines and disposed in alower layer of aggregates and an upper layer of fines, this separationof the material and disposition thereof in different layers beingaccomplished as a continuous operation.

A further object of my invention is to dispose the material to besintered in a layer or bed which increases in porosity from the top tothe bottom thereof so that, as the depth of the bed increases, theresistance to downward fiow of air therethrough decreases, renderingpossible rapid and complete sintering of the material by downdraftcombustion thereof.

Further objects and advantages of my invention will appear from thedetailed description.

In the drawings;

Figure 1is a fragmentary side view of the feed end of a sinteringmachine of the Dwight and Lloyd type, partly broken away, to which themethod of my invention is applicable;

Figure 2 is a section taken substantially on line 2-2 of Figure 1,looking in the direction of the arrows, the wind box and the shield infront of the feed hopper and screen being omitted for clearness ofillustration;

Figure 3 is a semi-diagrammatic section through the screen and gratestructure and associated parts illustrating the method of my inventionand the resulting bed of material to be sintered; and

Figure 4 is a semi-diagrammatic sectional view through the feed hopperand associated parts illustrating the present practice in depositing thematerial upon the grate surface.

This application is a division of my copending application for Sinteringmachine, filed March 21, 1930, Serial No. 437,649.

I have illustrated the method of my invention as used with a sinteringmachine of the Dwight andLloyd type, by way of example, for which it isparticularly well adapted though it maybe used with othertypes ofmachines, in its broader aspects. The sintering machine comprises a mainframe 1 of suitable construction carrying 00 tracks 2 upon which travelpallets 3 of known type. This machine has an endless track, comprisingan upper run and a lower run, and is provided with suitable means, suchas sprocket wheels, for elevating the pallets from the lower run to theupper run and propelling them along the latter. The pallets are providedwith grates and the pallets of the train on the upper run of the machineare in contact so as to provide a continuous traveling grate structure.

As the pallets travel along the upper run of the track they first passbeneath a feed hopper by means of which the material to be sintered isdelivered to the pallets and is leveled off by a gate member in thecontinued travel of the pallets, after which the pallets pass beneath asuitable device for igniting the material and then, in their continuedtravel, the pallets pass over wind boxes which are connected to suitablesuction means for creating a down-draft through the mass or layer ofmaterial on the pallets whereby combustion is propagated downwardlytherethrough.

When the pallets reach the delivery or discharge end of the track theypass downwardly about the same and sinter is discharged from thepallets. The construction and operation of machines of this type arewell known in the art and need not be illustrated or described here indetail.

A supplemental frame 4'is suitably secured to the main frame 1 andprojects upwardly therefrom. This supplemental frame is provided, at itsforward end, with uprights 5 which support a feed hopper 6 provided witha downwardly and forwardly inclined rear deflecting wall or plate 7. Thematerial to be sintered is delivered to this hopper 6by means of aswinging spout 8 which swings transversely of the hopper so as todistribute the material the full width thereof, this spout swinging onan axis extending lengthwise of the machine. Swinging spouts of thistype, and means for operating the same are well known in the art. It isthe present practice to dispose the hopper 6 somewhat closer to thepallets 3 than in Figure 1, the material being discharged from thehopper onto the pallets, after which the pallets pass beneath a gateplate 9 adjustably mounted, as by slot and bolt means 10, upon theuprights 5.

This plate has a central extension 9a which projects downwardly asuitable distance beyond the top of the pallets and serves to level offand remove the upper portion of the material upon the pallet so as toprovide a layer of uniform thickness. The pallet then passes beneath anignition device 11, commonly termed an ignition furnace, which serves toignite the material upon the pallet. Each pallet is provided with agrate structure 12 (Figure 3) provided with suitable openings for theflow of air and products of combustion therethrough. After the charge ofmaterial has been ignited, the pallet passes over a series of wind boxes3, in succession, these boxes being connected to suitable means forcreating a suction effect therein which serves to draw air downwardlythrough the material upon grate 12 so as to propagate combustiondownwardly through such material. This method of sintering is inaccordance with present practice and is well understood in the art.

The method of disposing the material to be sintered upon the gratesurface, in accordance with present practice, is illustrated in Figure4. As previously pointed out, it is the present practice to dischargethe material from spout 8 into the feed hopper 6, this material beingthen discharged from the feed hopper directly onto the moving grates ofthe pallets. The material is discharged upon the grates in the form of apile or ridge which is of approximately conical cross section, asindicated at 14 in Figure 4. In this pile or ridge of material, thecoarser particles of: aggregates, and the relatively minute particles orfines, are mixed indiscriminately and, as the pallets travel beneath thegate plate 9 the pile of material is leveled off to provide a layer ofsubstantially uniform thickness. In the layer of material thus produced,however, the fines and the aggregates are not segregated but, on thecontrary, are mixed together indiscriminately and a considerable portionof the fines rest directly upon the grate surface and act to stop up orclog the openings of the grate with the result that the air and productsof combustion cannot readily be drawn therethrough. In consequence, therate of combustion of the material is retarded with a resultantcurtailment in the production of the machine. I avoid this objection byproviding means for separating the fines and the aggregates of thematerial and then disposing the material in two layers upon the grate,the lower layer consisting of the aggregates and the upper layerconsisting of the fines.

For this purpose I provide a screen structure and means for supportingthe same for movement into and out of operative relation to the feedhopper 6. I

In Figure l I have shown a screen structure 15 which comprises asuitable frame and casing and a screen 16 disposed within the casing.This screenis operated by an electric motor 17, carried by the screenstructure, so as to facilitate passage of material over and through thescreen. The screen structure 15 is provided with mounting rollers 18which travel upon tracks 19 carried by the supplemental frame 4, thetracks and the rollers providing convenient means for moving the screenstructure into and out of operative relation to the feed hopper 6.Structure 15 is provided, at each side thereof, with an angle bracket 20suitably secured thereto, this bracket receiving an eye bolt 21 securedtherethrough. The eye of bolt 21 receives the eye of a second eye bolt22 adapted to be swung into and out of a slot in the outwardlyprojecting arm of an angle bracket 23 suitably secured to upright 5. Anut 24 screws onto eye bolt 22 and bears against the outwardlyprojecting arm of bracket 23 for holding the screen structure 15 inoperative relation to the hopper.

An angle strip 25, secured to the top of the casing of screen structure15, is disposed closely adjacent the rear wall of hopper 6 when thescreen structure is in the position illustrated. The casing of structure15 is provided with an opening through its top which, when the screenstructure is in operative position, registers with the lower end ofhopper 6.

The screen 16 is inclined downwardly and oppositely to the direction oftravel of the pallets 3. Wing members 26 project rearwardly from thescreen structure 15 and support a rod 27 upon which is mounted a curtainstructure. This curtain structure comprises a plurality of fiat strips28 mounted at their upper ends upon the rod 27 for free swingingmovement about the same. Each of these strips is bent, at its lowerportion, to provide an angularly disposed finger 29 which rests looselyupon the upper face of grates 12 of the pallets, as in Figure 3. Thematerial to be sintered is discharged from spout 8 into the H contra tothe direction of travel of with the grate and, in the continued travelthereof, the fines are deposited directly upon the lower layer 30 toform a superposed layer 31 of fines. It is to be noted that these finesare deposited upon the lower layer 30 as separation of the materialoccurs and, as the pallets pass beneath the gate plate 9, the upperlayer 31 is leveled ofi to uniform depth. By depositing the fines uponthe lower layer, immediately after separation of the fines from theaggregates, packing of the upper layer is prevented and this upper layer31 of fines is in a loose and fiufiy condition so that passage of airtherethrough, with resulting combustion after ignition of the upperlayer, is greatly facilitated. A further advantage of my invention isthat the material is separated into fines and aggregates and disposed ina lower layer of aggregates and an upper layer of fines, as a continuousoperation and during travel of the grate structure. By thus conditioningthe material to be sintered, I render it possible to operate thesintering machine at higher speed and obtain more complete'sintering ofthe material,- than is possible under present practice. This has thegreat advantage of both increasing the output of the machine andobtaining more complete sintering of the material.

Since the screen 16 is inclined downwardly and the pallets, and thematerial, including both fines and aggregates, is delivered onto theupper face of the screen adjacent the upper end thereof, as clearlyshown in Figs. 1 and 3, the fines which pass through the screen willincrease in size or coarseness toward the lower end of the screen. Thismeans that the layer of fines-which is deposited upon the lower layer ofaggregates will be of progressively increasing fineness from the bottomof the layer of fines to the top thereof, the fines having the greatestdegree of fineness being at the top of the layer. off the layer or bedof material so as to assure uniform thickness thereof, and this bed ofmaterial is composed of particles which increase in degree of finenessfrom the bottom of the bed to the top thereof. This graduated bed ofmaterial, while in a light andfiuify and unpacked condition, passesbeneath the ignition device 11 where the top of the layer'or bed isignited. By having the bed of .uniform thickness and in a light andfiuffy and unpacked condition, with the particles of in degree offineness from the bottom to the top of the bed, I assure rapid anduniform sintering of the entire bed for the full thickness thereof, thusrendering it possible to perform the sintering operation continuouslyand at appreciably higher speed than where the material to be sinteredis not deposited upon the pallet grate in this light and fluffy andunpacked condition and with the material of the bed graduated andincreasing in fineness from the top to the bottom thereof.

In the treatment of certain materials it may to deliver such materialsdirectly from the hopper 6 onto the pallet grates. To do this, it isonly necessary to release the eye bolts 22 and roll the screen structure15 rearwardly along the tracks 19 into a position com- The plate 9levelsthe bed graduated and increasingpletely withdrawn from beneath thehopper 6. During this movement of the screen structure, the strips 28 ofthe curtain drag along the grates of the pallet and donot interfere inany way with movement of the screen structure into inoperative position.-With the screen structure 15 disposed in inoperative position, thematerial delivered to hopper 6 is discharged therefrom directly onto thepallet grates, the operation of the machine, in all other respects,being the same as above set forth, with the exception that the materialis not separated into fines and aggregates and disposed upon the palletgrates in separate layers.

The screen structure 15 is of known type and need not be illustrated nordescribed in greater detail, it being sufficient that a suitable screenis provided for separating the material into fines and aggregates, andhas associated therewith means for disposing the aggregates in a lowerlayer upon the pallet grates, the fines being then disposed in a layersuperposed upon such lower layer. There are a number of screenstructures which may be adapted for use on sintering machines, and anysuitable screen structure may be employed for this purpose.

The spout 8 delivers the material to be sintered, which materialincludes intermixed fines and aggregates, to the screen' 16 at the upperend thereof. This material passes downwardly over the screen, the finerparticles passing through the upper portion of the screen, the particleswhich pass through the screen increasing in coarseness or size towardthe lower end of the screen. The coarsest particles or aggregates aredelivered from the lower end of the screen onto the grate surface, asabove described. In this manner, the material to be sintered isdeposited upon the grate structure in a bed of predetermined depth, andthe particles of material increase in degree of fineness from the bottomof this bed to the top thereof, the coarsest particles or aggregatesbeing at particles being at the top. The material is thus gradedthroughoutithe depth of the bed, which assures both rapid and thoroughsintering of the material.

What I claim is:

The method of sintering material containing particles of varying degreesof fineness, which comprises passing the material downward over aninclined screen and thereby separating and graduating the particles inaccordance with differences in degree of fineness thereof, depositingthe graduated particles of material from the screen directly upon agrate while maintaining undisturbed the graduation by the screen of thematerial particles and during relative movement between the screen andthe grate, thereby depositing the material upon the grate in a bed withthe largest particles at the bottom of the bed and the particlesgraduated as to degree of fineness and increasing in fineness throughoutthe entire depth of to the top thereof, and sintering the resultant bedof material by downdraft combustion initiated at the top. surface of thebed.

EDWARD W. SHALLOCK.

the bottom and the finest the bed and from the bottom

